The RX Bandits have become one of my favorite bands, but the only suggestions I get for bands like them are Circa Survive, The Dear Hunter, Fall of Troy, etc, and I don't really like these bands. I do like The Sound of Animals Fighting, the RXB side project.

i love the fall of troy and rx bandits, as does my drummer, and we were really into melodic math rock stuff. check out tera melos untitled/self titled album (the later stuff is really different and a little too goofy for my taste)

I'm on the Ska end of Liking RxBandits so I'll give you my suggestions leaning mostly that way. Maps & Atlases Suicide Machines, Streetlight Manifesto, Let's Go Bowling. Except for Maps & Atlases (who opened for RxB a few years back) these are ska bands, not the technical musical peak that RXB hit at their end.